Oil Filter choice for race engine

[smckeown]

I have read that oil filters don't filter oil when engines are working at high RPMs, due to the bypass valve fikcing in as it's cant meet the flow requirements of the oil at that hih RPM.

So this is fine for road cars as the majority of the time is spent at low to medium revs. Whereas race engine are the opposite.

So firstly is this a problem for race engines fitted with OE filter. And should larger filters be fitted that have greater capacities and therefore the bypass valve kicks in later.

cheers
sean

[GavinPearson]

I'd contact the technical department of a company like Fram, they can tell you what the best option should be for your situation.

I think you need to explain to them your definition of high revs too - running from 5 to 7K, 6 to 8, 7 to 9 etc.

[knighty]

I have worked in the lubrications system department for a major motor manufacturer for 2 years so should be able to shed some light on this for you……..the bypass valve in an oil filter is rated at 1 bar delta PSI……..this means that it will only open when the filter media (paper) becomes clogged with contaminants….or……when the oil is too cold and vioscous……the 1 bar figure is the difference in pressure either side of the filter media, once the delta is more than 1 bar, it will open……the principle of operation is “any oil is better than no oil”…….all the major filter manufacturers like Mann+Hummel and Fram work on this principle……….if you are really worried about high flow at increased revs, just fit a taller filter which will contain more paper area, then you can be assured the pressure drop across the filter media is minimal and the bypass valve will never open at high RPM………but don’t start fitting filters without a bypass valve fitted, as one day the filter will collapse and kill your engine, I have seen it happen………I must say some of the motor manufacturers are taking the pi55 and fitting very small and restrictive oil filters, all in an effort to save cost, so having a bigger filter is a good thing

[smckeown]

knighty said:

I have worked in the lubrications system department for a major motor manufacturer for 2 years so should be able to shed some light on this for you……..the bypass valve in an oil filter is rated at 1 bar delta PSI……..this means that it will only open when the filter media (paper) becomes clogged with contaminants….or……when the oil is too cold and vioscous……the 1 bar figure is the difference in pressure either side of the filter media, once the delta is more than 1 bar, it will open……the principle of operation is “any oil is better than no oil”…….all the major filter manufacturers like Mann+Hummel and Fram work on this principle……….if you are really worried about high flow at increased revs, just fit a taller filter which will contain more paper area, then you can be assured the pressure drop across the filter media is minimal and the bypass valve will never open at high RPM………but don’t start fitting filters without a bypass valve fitted, as one day the filter will collapse and kill your engine, I have seen it happen………I must say some of the motor manufacturers are taking the pi55 and fitting very small and restrictive oil filters, all in an effort to save cost, so having a bigger filter is a good thing

Very interesting, so it does seem appopriate for race cars to have different (larger) oil filters than their OE ver4sions, as they spend more of their life at higher RPMs.

Can you explain this area more "difference in pressure either side of the filter media"

thanks
sean

[smckeown]

interesting you mention not fitting oil filters without bypass valves.

Reading A Graham Bell's four stroke performance tuning book tonight, he advises all race engines to fit oil filters without the bypass valves, I believe to ensure filtration is always performed even when pressure/revs increases.

I see that Mann & Hummel sell filters for my car with and without bypass valves.

[GavinPearson]

I'd agree with knighty, any oil is better than none so having a bypass is a good thing.

In engineering terms it boils down to the failure mode effects analysis and what you do about it - if the bypassless filter is used and it clogs you seize the engine. If the bypass filter is used and it clogs the engine lives to see another day.

If you are going racing then you will probably be maintaining the car well, as a guide I would run the engine in and change the filter and oil before the first race.

In a less than ideal world you will change the oil and filter before every race, but if the oil is still good that's a waste. You may want to use an oil analysis firm to look at wear metals and fuel in an oil sample - if there is nothing to worry about then don't bother changing it.

In the absence of any other information I would change the filter for every event given how cheap they are.

[smckeown]

GavinPearson said:

I'd agree with knighty, any oil is better than none so having a bypass is a good thing.

In engineering terms it boils down to the failure mode effects analysis and what you do about it - if the bypassless filter is used and it clogs you seize the engine. If the bypass filter is used and it clogs the engine lives to see another day.

If you are going racing then you will probably be maintaining the car well, as a guide I would run the engine in and change the filter and oil before the first race.

In a less than ideal world you will change the oil and filter before every race, but if the oil is still good that's a waste. You may want to use an oil analysis firm to look at wear metals and fuel in an oil sample - if there is nothing to worry about then don't bother changing it.

In the absence of any other information I would change the filter for every event given how cheap they are.

yes race oil and filter has always been changed after every event.

I have since read that opie oils recommend 8-12 hours of race running time before the need to change both

I'm also looking into an oil analysis firms, that would be interesting, especially as I have had overfueling problems before

[knighty]

if the oil filter doesnt contain a bypass valve, I can assure you it will have one mounted close by inside the engine.....this is a simple cost save, as you dont need to throw it away!.....the pressure drop is caused simply by the effort taken to push the oil through the media/paper.....when the oil is hot its minimal.....when the oil is cold its very significant, hence the bypass filter is needed.......imagine trying to pump honey through thick tissue paper.....it just dosent happen......the bottom line is always fit a filter with a bypass valve fitted.

[smckeown]

I've been doing more research, like here:

http://www.vfrworld.com/tex_vfr/tech/filters.htm

The bottom line is for race cars a higher bypass opening pressure is better. For my car the Mann & Hummel filter Bypass Valve Opening Pressure is 1.5 bar / 22 psi; I believe OEM/aftermarket ones are signiifcant lower.

Along with it's impoved filtration this may be a happy compromise. They are not expensive either, in fact I can get them cheaper than OE or quality aftermarket items if purchase a few at a time.

[phumy]

smckeown said:

I've been doing more research, like here:

http://www.vfrworld.com/tex_vfr/tech/filters.htm

The bottom line is for race cars a higher bypass opening pressure is better. For my car the Mann & Hummel filter Bypass Valve Opening Pressure is 1.5 bar / 22 psi; I believe OEM/aftermarket ones are signiifcant lower.

Along with it's impoved filtration this may be a happy compromise. They are not expensive either, in fact I can get them cheaper than OE or quality aftermarket items if purchase a few at a time.

Surely that would be a differential pressure across the inlet and outlet of the filter?

Normal oil system pressure would render that bypass to be open all the time, i suspect.

[smckeown]

phumy said:

smckeown said:

I've been doing more research, like here:

http://www.vfrworld.com/tex_vfr/tech/filters.htm

The bottom line is for race cars a higher bypass opening pressure is better. For my car the Mann & Hummel filter Bypass Valve Opening Pressure is 1.5 bar / 22 psi; I believe OEM/aftermarket ones are signiifcant lower.

Along with it's impoved filtration this may be a happy compromise. They are not expensive either, in fact I can get them cheaper than OE or quality aftermarket items if purchase a few at a time.

Surely that would be a differential pressure across the inlet and outlet of the filter?

Normal oil system pressure would render that bypass to be open all the time, i suspect.

So if you read knighty's post above it's the pressure difference betwen either side of the filter medium, ie how hard it is to push the oil through the filter. It's not the oil pressure within the engine.

[v8ian]

We used to use an OBERG filter, its big advantage, you can strip, inspect, easily clean, and refit in minuites.
http://www.obergraceproducts.com/
Ian

[phumy]

smckeown said:

phumy said:

smckeown said:

I've been doing more research, like here:

http://www.vfrworld.com/tex_vfr/tech/filters.htm

The bottom line is for race cars a higher bypass opening pressure is better. For my car the Mann & Hummel filter Bypass Valve Opening Pressure is 1.5 bar / 22 psi; I believe OEM/aftermarket ones are signiifcant lower.

Along with it's impoved filtration this may be a happy compromise. They are not expensive either, in fact I can get them cheaper than OE or quality aftermarket items if purchase a few at a time.

Surely that would be a differential pressure across the inlet and outlet of the filter?

Normal oil system pressure would render that bypass to be open all the time, i suspect.

So if you read knighty's post above it's the pressure difference betwen either side of the filter medium, ie how hard it is to push the oil through the filter. It's not the oil pressure within the engine.

Sorry i stand corrected, i didnt read his note on that. The oil system pressure relief is there to govern any excess pressure within the engine system normally at the oil pump outlet, this normally would come into effect at start up on a cold engine when the oil viscosity is high.

Just an aside, i had a problem on an Audi many years ago now with the oil pressure buzzer/sender, (now known as a common problem on the older Audis), anyway in my ignorance, i decided to pull the sump off and check the oil pump, when i got the pump off and stripped it down i found that the internal oil pressure relief spring was about 4mm shorter than a new one and quite some scoring in the valve bore. So i can only assume that the relief could have been lifting much earlier than it was designed too, given that the spring was shorter and not giving the correct tension that it should. I decided in the end to fit the new pump and it wasnt till it was all rebuilt that i found out it was the sender/buzzer that was at fault. Learning curve was steep that week.

[knighty]

correct.....when I first learnt about this it threw me too, as the manufacturer in question labelled the bypass valve cracking-open pressure as "14.5 DPSI"....so I thought to my self "what the hell is DPSI????"......after phoning them , it simply meant Delta Pounds Per Square Inch...Delta meaning "the difference between!........so for example if you have 5 bar at the entry to the filter and 4.5 bar on the outlet, the bypass valve will NOT open......but say on a cold frosty morning and you have 5 bar on the inlet and 2 bar on the outlet, the balve WILL open.

smckeown said:

phumy said:

smckeown said:

I've been doing more research, like here:

http://www.vfrworld.com/tex_vfr/tech/filters.htm

The bottom line is for race cars a higher bypass opening pressure is better. For my car the Mann & Hummel filter Bypass Valve Opening Pressure is 1.5 bar / 22 psi; I believe OEM/aftermarket ones are signiifcant lower.

Along with it's impoved filtration this may be a happy compromise. They are not expensive either, in fact I can get them cheaper than OE or quality aftermarket items if purchase a few at a time.

Surely that would be a differential pressure across the inlet and outlet of the filter?

Normal oil system pressure would render that bypass to be open all the time, i suspect.

So if you read knighty's post above it's the pressure difference betwen either side of the filter medium, ie how hard it is to push the oil through the filter. It's not the oil pressure within the engine.

[smckeown]

Who ever first mentioned Mann & Hummell filters i'd like to shake your hand vigerously and thank you.

I ordered some and compared them to the filters I was previously using.

Fascinating the difference...

http://track-monkey.co.uk/oil_filter.htm

cheers
sean

[knighty]

Mann+hummel are the best filter supplier full stop.........Fram are a load of ste, and do not deserve the praise they get from some quarters......... I often find that hardly anyone has ever cut open a spin-on oil filter to see the difference between a good and bad design....... you will notice all filter paper pleats in any Mann+Hummel Filter is embossed with dimples so it dosent stick together, therefore maintains a constant filter paper area for constant flow and therefore a minimal pressure drop.......a simple idea that works so well.

[eliot]

I've seen fram filters get sgged of on the internet - so was suprised to see them fitted on many of the top fuel cars at santapod:
http://www.mez.co.uk/dcam/DSCF1704.JPG
I think this is a fram also:
http://www.mez.co.uk/dcam/DSCF1691.JPG

Edited by eliot on Friday 4th April 21:02